I would argue that it is more immoral to allow uncertified people to bring loaded guns to work vs. denying one employee to carry. What moral person prioritizes one person over a group of people.

I'll answer TG's question to Shortwave:
Carry something(s) other than a gun.

No one ever died from dropping mace or a bat. It isn't like guns are force fields that prevent violence. They just provide another option when threatened - an option that may actually increase your likelihood of being killed in some situations. There is no panacea for violent crime.